hi there, typical newb post...

just picked up a 96 civic coupe auto trans with 273km on it.. it has an odd idle issue.

when cold and started it idles around 1500 - 1700 .. once it warms up (3 - 4 min) it dives down to about 1000 rpm and seems to want to sit where it should be around 800 .. but it bounces back up to around 1700 then down, then up, then down .. you get the idea.. LOL

it's smooth at any rpm .. not missing or anything..

where should I start?

i do know that there's a small fuel leak somewhere in or near the engine bay as I can smell it when it's running, or after run. all injectors look dry.

sorry, that's all the info i can give at the moment... it's was just dropped off last night and i had a mere 30min of light left to look at it.

thanks
ps. this is my first honda so i'm totally new

 

well, the bouncing idle is actually a fairly common issue.... first step, make sure there is no air in the coolant system

 

WOW! .. never thought i'd be starting there. thanks.. I'll try and do that tonight.

 

yeah, our hondas have a Idle Air Control Valve that uses coolant to control the idle.... if theres air in the coolant, then it acts up...

 

makes sense. wondered why the IAC was so pricey (i work at a parts store lol) just happened to check it

 

actually, next step would be to clean it... there a how ot in the diy routine maintenance section

 

well, burped the system.. still seems to have the issue.

turns out this is an Si .. seems that makes a difference for the IAC too. sorry about that misinformation. I guess I can still take it apart and see how bad it looks inside unless anyone has any other suggestions.

thanks

 

I didn't think there was such a thing as an automatic Si. Someone may have been swapping parts around and you may not have a set that can work together properly. The IACV is different for automatic (3 wire) versus manual (2 wire).

Edit: It appears that you may be in Canada. The Canadian Si is basically what was the EX in the USA. It should have VTEC engine, horizontal flow through the throttle body, and 3 - wire IACV on the bottom of the throttle body.

 

yes, sorry, I'm in Canada.

if the weather would improve I could actually get some time to check things out..

or being that it's an auto .. would that mean I should be looking at something else as causing the idle floating?

guess I'm looking for this under the TB

 

sorry to bring this back up after so long, just haven't had any time to work on the car and the weather has sucked royally around here.

about 2 weeks ago I was at the wrecker and grabbed a spare MAP sensor and tried that.. same results.

today managed to find a spare hour to play. ran the car for a good hour, letting it fully get up to temp with the rad cap off and was able to properly get all the air out of the system. it bubbled and frothed a lot spitting air out. ran it to the point that the entire cooling system was circulating and the electric fan cycled on and off about 4 times when it should.

the idle has now smoothed out and no longer searches between 1000 - 1700. yay 1 problem sort of resolved.

now, it sits steady at ~ 1600 rpm, which, to me is far too high of an idle for this car. when put into R or D it'll drop and stay steady at around 1000 rpm.

what's my next step or test to try and bring this now steady idle down to where it should be while in park ?

should I disconnect the battery for 30min and see if it'll relearn a proper idle? i have no CEL or codes in the system. so the car thinks it's okay but obviously, a 1600 rpm idle is too high.

suggestions?

thanks again gurus